Canton is still working fine.
If you use an outside antenna, time to check the coax and connectors.
If you change antennas often, check the BNC connector on the scanner for movement. Once they move, it can break the solder joint inside.
Look at what is between you and the transmitters. Weather, leaves, electrical interference, other radio systems etc all can degrade your monitoring. Remember, a scanner is a broadband receiver. That usually means it doesn't do any one band great, it just does all of them OK.
chris